Hobbing machine



April 13, 1943.

C. H. SCHURR ETAL yHOBBING MACHINE Filed Aug. 4, 1934 4 Sheets-Sheet l'April 13, l943- c. H. scHURR ETAL 2,316,367'

HOBBING MACHINE Filed Aug. 4, 1954 4 Sheets-Sheet 2 EEZ M5/64 mv//WY 4TTORNEYS April 13, C, H SCHURR ETAL HOBBING MACHINE Filed Aug. 4, 1934 4SheelZS--Sheet 3 INVENToRs BY @fC M/arner ATTORNEYS Patented pr. 13,1943 HOBBING DIA'CHINE Charles II. Schurr and Homer C. Warner,Cleveland, Ohio, assignors to The Lees-Bradner Com pany, Cleveland,Ohio, a corporation of Ohio Application August 4, 1934, Serial No.'738,464

9 Claims.

This invention relates to machine tools and is particularly applicableto tools for cutting noncircular objects.

I It is an object of the invention to provide an improved machine toolwhich will produce work of extreme accuracy.

Another object is to provide an improved machine tool which will berapid in operation.

Another object is to provide an improved machiney tool in which thepositions of the work and tool will be at all times positivelycontrolled.

y Another object is to provide an improved machine tool which will beeconomical of floor space.

mother object is to provide an improved machine tool which will besilent in operation.

Another object is to provide an improved machine tool which may beeasily operated.

Other objects will hereinafter appear.

The invention will be better understood from ythe description of onepractical embodiment thereof, illustrated in the accompanying drawings,in which;

Figure 1 is a front elevational view, parts being broken away and partsbeing shown in section,

of a machine tool embodying the invention and designed for theproduction of gears and similar articles;

Figure 2 is a fragmentary front view with parts broken away and parts insection of the machine K scale;

Figure 8 is a fragmentary sectional view taken on the line VIII-VIII ofFigure 7;

Figure 9 is a fragmentary sectional view taken on the line IX-IX ofFigure 7;

Figure 10 is a fragmentary sectional view taken on the line X-X ofFigure 9;

Figure 11 is a sectional view taken on the line Xl--XI of Figure 1;

Figure 12 is a fragmentary sectional View taken on the line XLI-XII ofFigure 1; and

Figure 13 is a diagrammatic view of the electrical connections of theapparatus.

The machine illustrated consists of a supporting base I upon which ismounted a frame 2.

The frame 2 is formed with upwardly extending ways 3 upon which areslidably mounted the tool head and its associated mechanism, to befurther described hereinafter.

The frame also has formed upon it a hollow projecting casing portion 4in which are mounted the parts of the mechanism which support andcontrol the work, and vertical ways 5 upon which are slidably carried atail stock 6.

Mounted upon the base i is the main driving motor l, shown as providedwith a pulley 8 from which belts 9 pass to a pulley I0 secured to theend of a horizontal shaft II journaled in tne frame. Also secured to theshaft I I are a bevelled gear I2 and a spur gear I3, from the former ofwhich power is transmitted to the cutter or tool and from the latter tothe work, lead, and feed mechanisms.

Mounted in bearings on the frame is a vertically extending shaft !4having keyed to its lower end a bevelled gear I5 meshing with bevelledgear I2 and also having keyed to ita pulley I6 for driving the pumpingmechanism which will be hereinafter described. v

The upper end of the shaft I4 is splined as indicated at I'I, andslidable upon it is a bevelled gear I8 which is mounted in bearings in acarriage I9 engaging the ways 3 above referred to.

The carriage I9 is itself provided with horizontal ways upon which ismounted a slide 2i. A horizontal shaft 22 is mounted in bearings uponcarrier I9 and provided with a bevelled gear 23 meshing with gear I8.This shaft is splined to telescopically engage with a horizontal shaft24 having complementary splines and mounted in bearings within the slide2 I.

The end of shaft 24 remote from shaft 22 has `formed integrally with ita bevelled gear 25 which meshes with a bevelled gear 26 carried by atool supporting head 2'! which is secured to the end of the slide 2l lbybolts or the like so as to beA angularly adjustable about the axis ofshafts 22 and 24. This gear is keyed to a shaft 28 which, throughreduction gearing 29, drives a gear 30 keyed to the cutter spindle 3Iwhich is supported in bearings in head 2l parallel to shaft 28 and isshown provided with a hob 32.

Meshing with gear I3 is a gear 33 splined to a horizontal shaft 34journalled in the frame 2 and extending through housing 4. The outer endof this shaft is provided with a change gear 35 which drives, throughchange gears 36 and 3l, horizontal shaft 39.

An idler 38 meshes .with gear 35 and .with a gear 4I) secured to ahorizontal shaft 4I to which is also keyed a gear 42, forming a part ofa differential mechanism most clearly shown in Figure 5.

The differential mechanism includes idlers 43 journalled in a cage 44,supported by a shaft 45 coaxial with shaft 4| and driven by means to behereinafter explained, and also a gear 46 keyed to a hollow shaft 4lsurrounding shaft 4| and provided with a worm 48 which meshes with aworm wheel 49. The worm wheel 49 is keyed to a vertically extending workspindle 59, mounted in suitable bearings in housing 4.

From the above, it will be apparent that when motor 'I is operated itdrives, through pulley 8, belts 9, and pulley I9, the shaft Il. To thisis positively connected, by gears I2, l5, shaft i4, gears I8 and 23,shafts 22 and 24, gears 25 and 25, shaft 28, and gears 29 and 39, thecutter spindle 3|. Hence there is imparted to the cutter 32 a rotationwhich is always in fixed relation to the rotation of shaft I I.

Also, power is Vtransmitted `from shaft If through gears I3 and 33,shaft 34,'gears 35, 36 and 49, shaft 4|, gears 42, 43 and 49, shaft 41,worm 48, and worm wheel 49, to the work spindle 50, this rotationalso'being directly related to the rotation of shaft I excepting for anysuch variation as may be produced by the rotation of differential cage44 by shaft 45.

'I'hus the two trains of gearing already described produce the properrelative rotation of hob and work which would be necessary to generategear teeth upon a work blank mounted on spindle 59, and if the gear tobe produced is of `the ordinary spur type having teeth parallel itsaxis, no increment of rotation need be added to the differentialmechanism referred to, but it would be only necessary, if the face ofthe gear were wide, to provide an axial feedor lead movement of thecutter relative the work in the drection of the axis of the latter.

However, as it is desired that the machine tool may be used in theproduction of other types of products, such as gears having helicallydisposed teeth, means have been provided for imparting an increment ofrotation related to the relative position of the tool axially of thework.

As previously mentioned, the change gears 36 and,3'| drive a horizontalshaft 39 mounted within the frame of the machine. vided with a worm 5|meshing with a worm wheel 52 secured to a shaft 5,3 horizontallyjournalled in the frame and extending transversely of the machine, asmost clearly shown in Figures l, 7

and 9. Keyed to shaft 53 is a gear 54 and ro- .r

tatably mounted on the shaft is a sleeve 55 on the exterior of which areformed aV gear 55 and a worm 51.

Parallel to shaft 53 and mounted above it are two coaxial shafts 58 and59, therformer having keyed to it a gear 58 meshing with gear :54 andthe latter a gear Bl meshing with gear-56. The adjacent ends of theseshafts are provided with bevelled pinions 62 which form parts 4of adifferential mechanism including idler bevelled pinions 63 and a cage64. The latter has formed on its exterior a worm wheel G5 with whichmeshes a worm 66 secured to the shaft 61 of an electric motor BB.

The worm 51 meshes with a worm wheel 69, which has passing through .it apin '19, while `mounted coaxially with the worm wheel is a cam Il havinga radially extending projection T2. Projections on the upper surface ofthe cam lie in the path of the lower Aend of pin 'HL so that.`

This shaft is pro- Lr as the worm wheel 58 is moved in one direction thepin will contact in one of these projections and move the cam with it,while upon reversal of the worm wheel, the pin will be retracted fromthe projection, allowing the cam to remain in stationary position untilthe pin has reached another projection which it contacts to move the camin the opposite direction. Hence, by proper adjustment, of the abutmentsupon the cam, the worm wheel may make an oscillation of any desirednumber of degrees less than a complete revolution, while the cam needonly move through ya relatively few degrees.

Mounted upon a vertical pivot i3 is a bell crank lever having abifurcated arm 74 and an arm 15 provided with two rollers 'I6 arrangedin the Path of cam 12, so that the lever will be swung in one directionwhen projection l2 engages one roller and in the other when thisprojection engages the other.

The projection 'E2 is formed concentrically of the cam axis and soprovides a quick movement of the rollers in either direction, afterwhich,.and during the cutting or return stroke, one .or-the other ofthese rollers dwells upon this concentric surface.

The forked end of arm 'I4-embraces a pin 'I1 carried by a collarf8.adjustablyfsecured toa -rod 79 which is horizontally supported-foraxialreciprocation within the frame. -Secured to the rod, as by athreaded sleeve 79a, isa slide ,8D provided on one surface with rackteeth 8| engagingthe gear 82 fixed to a vertical shaft 83. A springJQbis interposed between the sleeve and slide to permit a small relative`movement of these parts. The shaft 83 extends upward withinthe carriageI9 where its upper end is splined as indicated at 84 and carries a gear85 meshing witha rack Bsecured to the slide 2 I. Therefore, when the rod19 is reciprocated, it rotates shaft 83 `which in turn, through thegear` 85 and rack 8S, moves theslide toward or from the work, serving tofeed the cutter into depth and to retract it after the outting operationhas been completed.

An adjustable stop 20a is secured-to thecarriage in position -to engagean abutment 21a on the slide, and so positively limit the depthto whichthe cutter may be fed. The parts are so adjusted that at all times whilecutting, .the abutment .is pressed against the stop by the compressionof spring 19h.

Slidable through the frame is a Ahorizontal rod 81 extending closelyadjacent the downwardly projecting pin 81a secured inthe cam 1I andprovided with two collars in the-path of the pin. The outer end of therod is connected to an electric switch 89 and serves-to control motors'l and 68 in a manner which will be hereinafter `described.

Keyed to shaft 59 is a skew gear 90 meshing with a gear 9| secured to ashaft 92 whichextends to the exterior of the frame. Here Ait isconnected with a parallel, shaft `23 by change gears asiase'? 3 changegears 94, shaft 93, gears 56 and 91, the lead screw 98 is positivelyconnected to worm wheel 69, and that if motor 68 remains stationary4these parts are geared back through gears 62, 63, and 54, shaft 53,worm wheel 52, worm'5l, change gears 35 and 31, to shaft 54, which, asabove pointed. out, constitutes part of the positive drive between thetool and cutter.

Cut into the shaft 93 is a worm |09 which meshes with a worm wheel lilisecured to a transverse horizontal shaft |92. This shaft extends throughthe frame passing beneath worm wheel 49 to the exterior of the framewhere it is provided with a gear |93, which drives, through change gearsIM, a gear |05. These gears are enclosed within a cover |08 secured tothe frame.

' Gear |05 is keyed to a shaft |51 extending within the frame providedwith a worm |08 meshing with a worm wheel |59. ,The worm wheel |9 iskeyed to shaft i5 which, as above mentioned,

carries the cage of the differential mechanism shown in Figure 5. Itwill thus be seen that this cage is positively geared to the shaft 93and so is controlled in its motion by the lead or feed of the toolaxially of the work.

By suitably selecting change gears |54, the cage '44 may therefore Iberotated to add any desired lincrement to the rotation of the workspindle in proportion to the axial travel of the tool, thus simplyproviding for producing gears of any desired helix angle. If gearshaving teeth parallel their axes are desired, the change gears |04 maybe omitted, and the worm |08 locked against rotation, which may beaccomplished by having a low pitched worm which will be self-locking, orby any other desired means.

Motor 1 is of relatively high power and low speed in comparison withmotor 59, as its function is to drive the mechanism while performing itswork, while the function of the latter mentioned motor is to drive theparts on their return, and it may therefore be of less power and driveat a *higher speed.

When motor 1 is being actuated and motor 68 is stationary, the latter,having a low-pitched lworm at 66, locks the cage 64 against rotation,

so that differential mechanism at this point acts merely as a set ofidler gears, the various drives from shaft being as above described.

f When, however, motor 1 is allowed to remain stationary and motor 68 isoperated, cage 64 is driven by worm 65. Worm 5| locks, due to its lowpitch, worm wheel 52 and shaft 53. Power is therefore transmittedthrough gears 5l and 90,

` the former driving, through gear 55, worm 51, and

worm wheel 59, the cam 1| which actuates the feed of the slide and theswitch 99. At the same time that this is happening, through gears 90 and9|, shaft 92, gears 94, shaft 99, gears 96 and 91, the power rotateslead screw 98 to return the slide lto its starting position. Therotation of shaft 93, through worm |58, worm wheel IDI, shaft, |2,

gears |93 to |55, worm |91, worm wheel |08, ro-

' tates cage 44 to impart an increment of rotation motor 1.

The worm wheel 69 of course rotates in an opposite direction when partsarebeing driven by motor 1 than when they are being driven by motor 63.

Asbest illustrated in Figure 1, the tail stock consists of a slide 6,mounted upon vertical ways 5 on'the frame.l This tail stock is providedwith a dead -center ||0 and with means for clamping ,the stock in placeconsisting of a bolt or cam provided with an actuating handle The deadcenter is, of course, in axial alignment with the work spindle 50.

The base is provided with an upwardly extending marginal flange ||2which forms a trough upon the top of the base adapted to catch coolantand direct it into the hollow of the base which constitutes, in effect,a tank for this material. Within this hollow of the base is a pump ||3provided with a vertically extending shaft ||4 supported in a column orpedestal ||5 which extends above the base. The upper end of the shaft isprovided with a pulley I6 around which Y passes a belt ||1 and is drivenby pulley l5 safety switches |25 to the switch 89.

mounted on shaft I4. The belt is maintained taut by an idler pulley |28adjustaoly carried upon an arm H9.

1 A cover |20 is secured to the frame and encloses gears to 38 and 40.

In Figure 13, the electric circuits controlling motors 1 and 68 areillustrated. Power is supplied by electric supply lines |2|, |22 and|23, from the latter of which it is led through a manually openablesafety switch |25 and limit VThe latter switch controls the relays 1aand 58a, associated with the motors 1 and 58 respectively, so that whenmoved to contacts 1b the former relay is actuated to supply electricityto motor 1, and when moved to contact 68D current is supplied to relay68a, operating motor 68. In one line to relay 58a is a magnetic hold-inswitch |25 which is automatically opened when the circuit to this relayis broken. Hence, when switch 89 moves from contacts 1b to contacts68h', both motors are stopped. Arranged in parallel with switch |26 is amanually operable starting switch |21, such as a push button, which maybe closed to furnish energy to relay 58a and start motor 58.

This current closes switch |26 which remains closedY until switch 99 isactuated by the cam mechanism above described.

The cycle of operation is as follows: With both motors stopped andcontacts 68hclosed, the operator inserts a piece of work in work spindle50. He then presses switch |21 which supplies curreni; to relay 59a,starting motor 68 andr closing switch |26. The motor 63 returns thecutter to the position for starting the cut and as it very nearlyreaches this position, actuates the cam 1| to feed it in to depth. -Justas this is done, it actuates switch 89 to close contacts 1b and opencontacts 68h. rIfhis, of course, actuates both relays, stopping motor 58and starting motor 1,

which drives the parts to perform the cut and then to back out thecutter when it actuates the switch 89, moving it to open contacts 1b andto close contacts 68h. This, as above mentioned, stops both motors,which, after removing the finished piece of work and supplying a newone, the operator can again start on their cycle by switch |21.

While a single machine unit is shown, a plurality of units may beassembled into one machine, as by being mounted on a turntable orturret, such for instance as that shown in our copending applicationSerial No. 567,276, led 0ctoner 6. 411.951, which :has natured :intoBatent 2,075,489, of AMarch :30,1937.

While we have described the illustrated .,embodiment of our inventioninzsome .-particularty,

obviously lmany f,other rembodiments, :variations .and modificationsthereof will readily ,o ccur;to thoseskilled in ,thisiart land we donot,:therefore, 'limit ourselves to` the precise detailsrshown ,anddescribed herein, ibuttclaim, asgour invention all embodiments,variations :and ',mcdications coming within the scope of thesulzijoined` claims.

We claim: 1. VVA machine tool comprising a `worlr spindle anda toolspindle, positive, gearing betweenv said fspindles, a differential insaid gearing,` meansffor feeding said tooland work spindles;relativeeach 4Vothergearng connected to said first mentoned gearing andto said feed means and including a differential, a source-of powerconnected-to said first mentioned gearing, ,connections between saidfeedmeans'and said first mentioned diier- ,ential, and 4a second sourceofpower connected Vto'one element of said, second.'mentionedgdiierential.

2. A machine tool comprisingarotatable'work Aspin'dleand arotatabletool'spindle, positivegearing between said spindles4 includinga=diierential,

-a source of power connected to f,said gearing, a

gear train connected tosaidfirst mentioned gearing `and including asecond differential, asec- :ond 'source Vof power connectedto-'oneelement of said second mentioned gdifferentiaL-leadtand feedmeans operated by-saidsecond-mentioned gearing beyond said differential,and positive ,gearing between said lead and feed-means;.and vsaid rstmentioneddifferential.

3.,A rmachine tool including -a work spindle and a tool spindle bothadapted .to rotate at relatively low speeds, ,speed v:reduction `gearingclosely adjacent and connected to the-work-spin- 4dlefspeedreductiongearing closely adjacentean'd connected `to 4the ,tool spindle,positive driving connections betweensaid speed reduction lgearings'causing rthe .spindles gto-rotate 1in predetermined relation,saiddriving --connections 'operating at relativelyyhign speed, meansformoving said spindles -relative each other connected to :said :drivingconnections, means `interposed vinwsaid driving vconnections Varying therelative rotation of said spindles and .,-operated -by the fmotion ofthespindles relative-eachother, a differential includedl inf said drivingconnections,

ya driving means connected to an elementv of the differential, andanother driving means connected to another element -of the differential,

4. lAhobbing.:machinehaving a work spindle .anda tool spindlecomprisin gadriveripositively `connected to bothsaidspindles; and-including fadifferential mechanism, a ypower ,delivering means, a non-reversiblepower .transmitting means connecting said power delivering means `tosaid differential, a second power delivering means, and a secondnon-reversible power transmitting means connecting said second,mentioned power delivering means to'saidmechanism.

45. `A hobbing machine 4having `a work. spindle and a, tool spindle,comprising a` ,drive positively .work spindle, n positive speedreduction gearing closelyadjacent andgconnectedto thetool spindle,Apositive driving connections between said speed reduction gearingscausing said -spindles to,rotate"in,predetermined relation andoperatingat-'relativelyhigh speed, a differential interposedin saiddrivingconnections, apower delivering means connected to one element ofsaid differential, and a secondpower delivering means `connected Vtoanother element ofthe diierential.

7. A hobbing machine includinga .work spindle and a `tool spindle, both,adapted to rotate latrelatively low speeds, positive speed reductiongearing closely ladjacent ,and connected to the work spindle, 1positivespeedreduction gearing Vclosely adjacent and connected to the toolspinlrile, 4positive -di'iving connections between said speedreductiongearings `causing said spindles Yto grotatein predeterminedrelation and operating--at relatively high speed, a differentialinterposed in said driving connections, a power delivering meansconnected to one element of said differential, and-a secondpowerdelivering means connectedV to another element of the differential,eachgofzthe connections between the power deliveririgmeans4 andthedifferential including a non-,reversible power transmitting means.

18. Ahobbing machine comprising a work spindle and a tool spindle,driving connections connecting said spindles, feed means arranged tomove ,the spindles relative each other in the di- ;rection ofthe axis ofone of them, second feed means arrangedlto vmove said spindles relativeeach other; in-ia direction transverse said axis, a power deliveringmeans connected to saidlspin- .gdles 1and :to` bothsaid feed means, asecond Vpower 'deliveringmeans independently connected to both said feedmeans yand to one of thel spindles,

and controlling means selectively controlling vbot-,h .saidgpowerdelivering means.

Ahobbing, machine comprising a work spin- -dle;and,a tool spindle, feedmeans arranged to movelsaid spindles relative each other, positivepowertransmitting means between` the spindles causing them to rotateinpredetermined relation, said power; transmission including Aadifferential-having one element connected to said feed vmeans, drivingmeans connected to said power -transmission mechanism to rotateV bothspindles ,and=.operate said feed means, and a separate driving meansconnected to said feed means. `CI-lARLES HNSCHUR'R. HOMER C." WARNER.

